DIPTERA OF MINNESOTA. 105 



MUSCIDEA. 



The families of flies in the following pages, while they agree in 

 certain characteristics which formerly united them in one family, 

 Mtiscidac, at which time many of them were regarded as sub-families, 

 have latterly been given family rank. While they differ from each 

 other in certain characteristics, which present-day entomologists for 

 the most part regard as sufificient to establish the separate families, 

 they agree in the following common character : The antennae are al- 

 ways three-jointed, and always (with the exception of one genus,where 

 it is absent) with an arista, the palpi are never jointed ; pul villi always 

 present ; empodia wanting ; alulets well developed. 



BORBORIDAE. 



A family of about twenty-four North American species. The 

 smallest one in our collection, Limosina, whose larva lives in algae, 

 fungi, diseased potatoes, etc., is extremely minute, while Borhorns 

 is nearly or quite half an inch in length. 



These are brownish flies, found frequently in swarms about de- 

 composing organic matter, the larvae of some of the species living in 

 such material ; sewage, or dung, for example. 



We have taken in Minnesota : Borhorus equina, Fall. ; B. gcni- 

 culata, Meig. ; Liynosina, sp. 



AGROMYZIDAE. 



Very small flies, about 92 species in North America, the larvae 

 of some of the species feeding on plant lice. Other larvae have been 

 found in galls. 



Species taken in this state are : Agromysa ncptis, Loew. ; chthiphila 

 poly stigma, Meig. 



GEOMYZIDAE. 



A small family of small sized species. Sixteen are known in North 

 America (1904). As far as known the larvae live in the stems of 

 plants, and the adults are sometimes captured when using the beating 

 net upon plants and shrubbery. 



